U.S. Pat. No. 3,540,594 discloses an adapter for internal combustion engine oil filtering apparatus which provides for lubricating oil flow in parallel paths to a full flow filter and to a limited flow by-pass filter, without however, providing for flow from the by-pass filter to the engine galleries, but rather to the engine crankcase. In consequence, if the full flow filter should impede flow more than the by-pass filter, whether by channeling flow occuring in the by pass filter or for other reason, an engine could receive inadequate flow of lubricating oil to the engine galleries.